1. Field of the Invention
This invention relates to a tape editing apparatus having automatic tracking adjustment.
2. Description of the Related Art
When editing of a video tape in recent years, so called electronic editing to entirely electrically carry out editing without cutting the video tape is frequently adopted.
For such an electronic editing, it is required that at least two VTR (Video Tape Recorders) are used to wind or take up (so called a preroll) tapes of respective VTRs at a position forward of the editing point where editing is carried out, and thereafter to carry out a so called phase adjustment to adjust phase of respective regenerative signals of these VTRS, i.e., the phase of a control signal, the phase of a drum revolution, and the like. As such an electronic editing method, a method called an automatic editing is also known.
A tape editing apparatus based on such an electronic editing method having the ability to carry out automatic editing comprises in combination a plurality of Video Tape Recorders (VTRs), a controller (or computer), and associated equipments. As video tape recorders included in the tape editing apparatus, there are provided a video tape recorder for recording and a video tape recorder for reproduction. The operating procedure of the tape editing apparatus is conducted as follows. First, the operations of a plurality of video tape recorders are controlled on the basis of editing information input in advance into the controller (or computer). A video tape recorder corresponding to the editing source of the automatic tape editing apparatus provides necessary regenerative signals while suitably selecting them.
In the case of carrying out an automatic tracking adjustment in a typical automatic editing, the algorithm of the tape editing apparatus function adapted for carrying out a tracking automatic adjustment in the time period from when phase adjustment is carried out until the start of recording is as follows. When a command indicative of starting automatic editing is input preroll is conducted thereafter to allow the Edit Preset and the Play to be in an "ON" state. When both the Edit Preset and the Play have completely placed in "ON" state, the tape editing apparatus starts phase adjustment.
The editing function reproduces at an editing point an objective or target recorded program, etc. to record the reproduced content onto an editing point (cut-in point) located at an objective or target position on a recording tape. The above mentioned phase adjustment is an operation or manipulation for allowing the video tape recorders to be precisely started for editing at respective points (cut-in points) on the basis of time codes recorded on the respective tapes. For such a time code, there are two time codes of a VITC (Vertical Interval Time Code) for recording into a recording area in the helical direction and a LTC (Longitudinal Time Code) for recording in the length direction.
In order to carry out phase adjustment between at least two video tape recorders, one of the video tape recorders carries out variable speed reproduction so as to start editing on the basis of time codes that respective objective or target editing points (cut-in points) indicate by input ("ON" state) of a variable speed reproduction command (Var). If the phase adjustment operation by the variable speed reproduction which is the editing start pre-processing is completed, the tape editing apparatus allows the play command (Play) to be in "ON" state. Then, tracking adjustment is carried out by monitoring the RF envelope of a video signal.
Then, it is determined whether or not a servo lock is established in the tape running servo. In the case where the servo lock is not established, it is determined whether or not the above-mentioned operation should be repeatedly carried out and operation corresponding to the determined result is carried out. In contrast, in the case where the servo lock is established, a control command (Edit) for editing is caused to be placed in an "ON" state, thus to start the editing work from the editing point (cut-in point).
This automatic tape editing apparatus has, in addition to the above-mentioned function, a function to precisely and promptly carry out various operations such as high speed selection of cut of a material to be connected, determination of its leading position thereof and preset of a recording position of a master tape, etc. to conduct a desired editing.
However, in the case where the above-mentioned automatic tape editing apparatus is used to carry out an automatic tracking adjustment, it was necessary to operate buttons an operation panel manually for a time period until starting of recording at the time of phase adjustment, i.e., to adjust tracking until the cut-in point so that the tracking level becomes maximum. For this reason, prior to editing work using this apparatus, an editor had to consciously carry out tracking adjustment by a manual operation at the time of phase adjustment. While the tracking adjustment operation at the time of phase adjustment permits an editor to precisely automatically carry out a very fine editing after the tracking phase adjustment is satisfactorily carried out, in the event that an editor has forgotten this manual operation, there is high possibility that tracking errors may take place, resulting in noise on the picture. For this reason, the tracking adjustment at the time of an initial phase adjustment becomes very important. However, since it is necessary to carry out a manual tracking adjustment operation at the time of an initial phase adjustment, this would impose a burden on the editor.